Lime slab on vaulted cellar

[vegaman]

Hello,

I have a vaulted cellar 3m wide by 6metre long. The cellar is red brick, has two openings on the outside to ventilate. The cellar floor is clay.
The bricks are healthy, not damp. On the other hand the ground is wet for him.

I would like, above this vaulted cellar, to sink a 10cm chappe. Insulating lime / hemp screed with Type X vegetable concrete.

Currently above this cellar, it is filled with what is called machefer.Between the top of my vault and the ground there are about 40cm.

Several questions :
- Will the arch support the weight?
- I have no possibility of making a ventilated hedgehog because it is impossible to install a ventilated drain. Do I still have to make a hedgehog or can I pour this slab directly on the bottom (minus 10cm of course)?
- Can we improve the insulation by putting cork under the cap?
- What to put on around the slab at the wall / slab junction? cork?

Thank you

[PITMIX]

If your slab is 6x3m and 10cm thick it will be around 4120kg if it is standard concrete
It is not negligible.
But in vegetable concrete at max it's 630kg it's not the same ...
Cork is great for this application. You don't prefer insulating your house from the outside. ?

[elephant]

Given the stakes, I would still take formal advice from an architect ... (that he undertakes in writing)